<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title>程序员常用样式</title>
		<style>
			.mydiv{
				background-color: red;
				width: 300px;
				height: 300px;
				color: black;
				/*让div在网页上居中显示*/
				margin: 0 auto;
				/*文字对齐居中对齐*/
				text-align: center;
			}
			.uname{
				width: 450px;
				height: 40px;
				border-radius:20px ;
				/*边框宽度1像素、实线、红色边框*/
				/*border:1px solid red;*/
				border: 2px dot #299e59;
				background-color: aqua;
			}
		</style>
	</head>
	<body>
		<h1>背景样式</h1>
		<div class="mydiv">
			今天天气不错
		</div>
		<input type="text" style="background-color: red;"/>
		<h1>边框样式</h1>
		用户名<input type="text" class="uname"/>
	</body>
</html>